By contrast, a quantum computer uses qubits, which can be one and zero at the same time, at least until they are measured, at which point their states become defined. Because each qubit represents two states at once, the total number of states doubles with each added qubit. “You would need to devote every atom of planet Earth to store bits to describe that state of that quantum computer. The trip started with an actual quantum computer, its innards exposed, on display in the lobby of the Thomas J. Watson Research Center, in Yorktown Heights. Each quantum computation starts and ends with a string of ones and zeros — classical bits — at the top of this assembly.

Source: New York Times October 21, 2019 09:00 UTC